Artificial landscaping timber system

ABSTRACT

A landscaping timber unit comprises a plurality of hollow extrusion units and a pair of end caps. Each extrusion unit extends longitudinally from a first end to a second end thereof and has a bottom wall and an opposite top wall, and has opposite side walls extending between the top and bottom walls. The top, bottom and side walls collectively form a substantially rectangular cross section when viewed along the longitudinal axis. The extrusion units are stacked upon one another with their respective first ends proximate to one another, with their respective second ends proximate to one another, and with their respective longitudinal axes substantially parallel to one another. One end cap is affixed to the first ends of the stacked extrusion units, and the other end cap is affixed to the second ends of the stacked extrusion units. Each end cap has a first end configured to receive the end portions of the stacked extrusion units and a second end that includes an aperture for receiving an elongate rod-shaped spike therethrough. The end of the timber unit can be secured to the ground by driving the spike through the aperture into the ground.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/523,639, filed Nov. 20, 2003, titled “ARTIFICIAL LANDSCAPING TIMBER SYSTEM.”

TECHNICAL FIELD OF THE INVENTION

The current invention relates generally to landscaping timbers and, more particularly, to interlocking landscape timbers that link end-to-end using elongated spikes that are driven through aligned apertures and into the ground.

BACKGROUND OF THE INVENTION

Landscaping timbers are commonly used around the perimeter of children's outdoor play areas in order to retain a ground cover material, such as sand or shredded or chipped wood or the like, within the play area. Traditionally, landscaping timbers were made of wooden timbers that had been pressure-treated (i.e., infused with chemicals under pressure) to resist insects and rot. Recently, however, growing concern over childrens' potential exposure to the toxic preservatives used in pressure-treated wooden landscaping timbers has led to the development of “artificial” landscaping timbers formed primarily of plastic. These artificial timbers are commonly about four inches wide, about eight to twelve inches in height, and anywhere from about four to eight feet in length. It is known to make artificial timbers with interlocking end portions having apertures extending vertically therethrough for receiving long metal spikes. These spikes both secure the artificial timbers to one another and also secure the timbers to the ground. Typically the spikes are two to three feet long and about ¾ inch in diameter.

Currently, most plastic landscaping timbers are molded as a single piece (complete with their interlocking end portions) using the rotational molding process, also known as “rotomolding.” These artificial timbers are typically molded in standard lengths, e.g., approximately four or eight feet long. It will be appreciated that rotomolding large articles such as artificial landscaping timbers requires very large, expensive molds and large rotational molding equipment. In addition, production rates are usually slow, with individual cycle times on the order of 30 to 60 minutes per molding. Not surprisingly, both the capital investment and the production costs for rotomolded artificial timbers can be substantial. A need therefore exists, for an artificial landscaping timber system that does not require timbers produced by rotomolding, and preferably, one that utilizes timbers produced by process(es) that are less costly and/or more efficient than rotomolding.

During the installation of borders made from artificial landscaping timbers having a standard length, situations frequently arise where one or more timbers of non-standard length are required. For example, when constructing a timber border around the perimeter of a playground using timbers of a standard length, the final gap between the two ends of the border will often be shorter than the standard timber length. In another example, when a landscaping border made of timbers having a standard length ends at a pre-existing wall, the remaining gap is often a non-standard length. In such cases, it is necessary to provide a “custom length” timber to fill the gap.

Current artificial landscaping timber systems based on one-piece rotomolded plastic timbers typically use one of two approaches for providing timbers of “non-standard” length. The most common approach is to “adjust” the length of one-piece timbers by cutting off one of the original ends (with its interlocking features), discarding it, and then replacing that end with an optional adapter (having replacement interlocking features) that is glued, screwed or otherwise affixed to the remaining portion of the timber “shell.” This approach requires the installer to know in advance how many “non-standard length” timbers will be necessary for a particular job so that the proper number of adapters will be on hand. This can result in project delays if conditions change during installation and additional adapters must be obtained. Alternatively, the installer must maintain an inventory of adapter pieces (which are generally fairly expensive) to be sure that projects are not delayed. A need exists, therefore, for an artificial landscaping timber system which does not require optional adapter pieces to form non-standard length timbers.

The second approach used for providing timbers of “non-standard” length in systems using one-piece rotomolded plastic timbers is to simply to offer complete one-piece rotomolded “adapter timbers” in “fractional lengths,” e.g., ½, ⅓, ¼, ⅛, etc. the length of the standard length. These fractional length adapter timbers can be used in different combinations to obtain “intermediate” lengths without the need for field modification. However, precise length adjustments are not possible, and, as with the previous approach, the installer must plan very carefully to know in advance how many, and what size, fractional—length adapter timbers will be necessary for a particular job, or maintain an inventory of costly adapter timbers. A need exists, therefore, for an artificial landscaping timber system which does not require optional adapter timbers to form non-standard length timbers.

Another shortcoming observed in existing rotomolded artificial landscaping timbers is their tendency to cause the securing spikes to “back out” of the ground over time. Maintenance personnel must constantly monitor the condition of conventional plastic timbers and periodically re-drive the spikes into the ground, otherwise, the heads of the spikes will eventually protrude above the top of the timbers (instead of being flush or inset as originally installed) and become a hazard to children. It is believed that this spike “pull out” phenomena results from the fact that one-piece rotomolded plastic landscaping timbers are necessarily formed of a single polymer material, and this material must be stiff enough to prevent excessive distortion of the side walls of the timber when side loads are applied. Obviously, since these timbers are made from a single polymer material, the interlocking end portions of the timber (through which the securing spike is inserted) are made from the same stiff material as the side walls. As the entire landscape border is rigid and interconnected, lateral loads exerted on the top and sides of a timber will tend to “rock” that timber, as well as the adjacent timbers in the border. This rocking motion is believed to produce rotational torques in the timbers and their stiff end portions, which in turn result in vertical forces which are transmitted from the end portions to the spikes, slowly pulling them out of the ground. A normal size playground can accommodate dozens of children who constantly step on the top of the timber border, thus producing a never ending source of rocking/lifting forces which pull up the spikes over time. A need exists therefore, for a landscaping timber system which allows for slight movement of the timbers without pulling up the spikes.

SUMMARY OF THE INVENTION

The present invention disclosed and claimed herein comprises, in one aspect thereof, a landscaping timber unit comprises a plurality of hollow extrusion units and a pair of end caps. Each extrusion unit extends longitudinally from a first end to a second end thereof and has a bottom wall and an opposite top wall, and has opposite side walls extending between the top and bottom walls. The top, bottom and side walls collectively form a substantially rectangular cross section when viewed along the longitudinal axis. The extrusion units are stacked upon one another with their respective first ends proximate to one another, with their respective second ends proximate to one another, and with their respective longitudinal axes substantially parallel to one another. One end cap is affixed to the first ends of the stacked extrusion units, and the other end cap is affixed to the second ends of the stacked extrusion units. Each end cap has a first end configured to receive the end portions of the stacked extrusion units and a second end that includes an aperture for receiving an elongate rod-shaped spike therethrough. The end of the timber unit can be secured to the ground by driving the spike through the aperture into the ground.

The present invention disclosed and claimed herein comprises, in another aspect thereof, an artificial landscaping timber comprising a plurality of elongate extrusion units, a pair of end plates, and a plurality of end caps. Each extrusion unit has a continuous wall that circumscribes a longitudinal axis so as to define an interior bore having a substantially constant rectangular cross section when viewed along its longitudinal axis. The plurality of extrusion units are juxtaposed in a single file with their respective longitudinal axes parallel to one another and with their respective longitudinal ends even with one another to form an extrusion stack having an external perimeter and longitudinal ends. Each of the end plates is removably mounted one longitudinal end of the extrusion stack. Each end plate has a generally flat end portion surrounded by a side wall depending laterally therefrom. Each further has at least one aperture formed through the flat end portion. The generally flat end portions of each end plate has dimensions substantially equal to the dimensions of the longitudinal end of the extrusion stack and lies generally perpendicular to the longitudinal axes of the extrusion units when mounted on the extrusion stack. The side walls of each end plate are dimensioned to encircle the external perimeter of the extrusion stack when mounted thereon so as to maintain the alignment of the extrusion units in the extrusion stack. The aperture(s) of each end plate each are disposed to overlie a single one of the extrusion units and are dimensioned to form an opening at least as large as the interior bore of the overlain extrusion unit. Each end cap extends through one of the apertures of the end plates and is removably mounted in the end of one of the extrusion units. Each end cap has a body portion and a distal portion. The body portion of each end cap are dimensioned to fit within the bore of one of the extrusion units. The distal portion of each end cap have an aperture formed therethrough for receiving a securing spike and remain outside the bore of the extrusion unit when the end cap is mounted therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an artificial landscaping timber in accordance with one embodiment of the current invention;

FIG. 2 is a cross-sectional end view of the timber of FIG. 1 taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged cross-sectional end view of a single extrusion unit;

FIG. 4 is a perspective view of an end cap for the timber of FIG. 1;

FIG. 5 is a top view of the end cap of FIG. 4;

FIG. 6 is an end view of the end cap of FIG. 4;

FIG. 7 is a side elevation view of the end cap of FIG. 4;

FIG. 8 is a side view of an artificial landscaping timber in accordance with another embodiment of the current invention;

FIG. 9 is a perspective view of an end cap suitable for use with the timber of FIG. 8;

FIG. 10 is a top view of the end cap of FIG. 9;

FIG. 11 is an end view of the end cap of FIG. 9;

FIG. 12 is a side view of the end cap of FIG. 9;

FIG. 13 is a perspective view of an artificial landscaping timber similar to that of FIG. 1;

FIG. 14 is a perspective view of an artificial landscaping timber incorporating a non-stepped end cap in accordance with another embodiment of the current invention;

FIG. 15 is a perspective view of the non-stepped end cap of FIG. 14;

FIGS. 16 a-16 d show an artificial landscaping timber in accordance with yet another embodiment of the current invention. Specifically:

FIG. 16 a is a side view (with portions broken away) of the new embodiment;

FIG. 16 b is an end view thereof;

FIG. 16 c is an opposite end view thereof;

FIG. 16 d is a top view thereof;

FIG. 17 a is an end view of a two-aperture end plate for the timber of FIG. 16 a;

FIG. 17 b is a side view of thereof;

FIG. 18 is an end view of a one-aperture end plate for the timber of FIG. 16 a;

FIG. 19 is an end view of a three-aperture end plate for the timber of FIG. 16 a;

FIG. 20 is a side view (with portions broken away) of a timber in accordance with an alternative embodiment interconnected to the timber of FIG. 16 a;

FIG. 21 a is a perspective view of an end cap for the timber of FIG. 16 a;

FIG. 21 b is a top view of the end cap of FIG. 21 a;

FIG. 21 c a side view of the end cap of FIG. 21 a;

FIG. 21 d is a rear view of the end cap of FIG. 21 a; and

FIG. 22 is an enlarged partial cross-sectional view of the timber of FIG. 16 a.

DETAILED DESCRIPTION OF THE INVENTION

The current invention is described below in greater detail with reference to certain preferred embodiments illustrated in the accompanying drawings.

Referring now to FIG. 1, there is illustrated a side view of an artificial landscaping timber in accordance with one embodiment of the current invention. The timber 100 of this embodiment includes three hollow rectangular extrusion units 102 stacked on top of one another and a pair of end caps 104 fitted over the ends of the stacked extrusion units. Each of the end caps 104 includes a stepped portion 106 which has a height approximately one-half the overall height of the end cap. It will be appreciated that the end caps 104 may be attached to the extrusion units in either orientation, that is, with the stepped portion 106 being on top (as shown on the right side in FIG. 1) or with the stepped portion being on the bottom (as shown on the left side in FIG. 1). A pair of apertures 108 are provided in the stepped portion 106 to allow the timbers to be secured to one another and to the ground by means of a spike. An adjacent timber 100′ (shown in broken line) is shown adjacent to the right end of timber 100. The timber 100′ has an end cap 104′ which has the complimentary orientation to the end cap 104 of timber 100, allowing the stepped portions of the respective end caps to overlap. Securing spike 110 (shown in broken line) may be placed through the aligned apertures 108 and 108′ and driven into the ground to secure the two timbers together and to the ground. A recess 112 may be provided on the outer side of the end caps 104 to allow the head of spike 110 to remain below the surface so as not to present a hazard to children playing around the timbers. The end caps 104 may be secured to the extrusion units 102 by means of screws 114 or other removable fasteners, which are removably inserted through the end cap wall and into the wall of the underlying extrusion unit. Interior screws 116 or other similar fasteners may be used to hold the stacked extrusion units 102 to one another, or alternatively glues or other adhesives may be used.

In normal construction, the artificial landscape timber 100 is used in standard lengths like conventional (i.e. roto-molded) artificial landscape timbers. However, when a non-standard length timber is needed, the standard length timber 100 may be modified (i.e., shortened) without the need for optional adapter pieces or other additional parts. Specifically, the user first removes the appropriate end cap by removing the fasteners 114 and removing the end cap 104 from the extrusion units 102. The user then cuts off the extrusion units 102 at the appropriate length, i.e., by removing the exact length by which the timber is to be shortened. The original end cap 104 is then reinserted over the end of the (now shortened) extrusion units and reattached with the fasteners 114. Thus, the timber 100 may be modified to any length without the need to use optional end adapters or other additional parts. In addition, should the need arise for a timber having matched ends, i.e., where the stepped portion was on the same side (both on the top or both on the bottom) at each end, then one end cap of a standard unit may be removed, inverted, and then reattached without the need to cut or modify the extrusion units 102. This ability to easily modify the length of the standard length artificial timber without the need for any special adapter pieces or other additional parts is a significant advantage over the prior art artificial timbers.

Referring now to FIG. 2, there is shown a cross-sectional end view of an extrusion unit 102 taken along line 2-2 of FIG. 1. Each of the extrusion units 102 is a relatively thin walled structure having a substantially rectangular (preferably square) cross-section as shown. The extrusion units 102 may be formed of polyvinylchloride (PVC), with or without impact modifiers, high density polyethylene (HDPE), with or without fillers, or ABS type plastics. The plastic used for the extrusion units 102 may also contain pigments to provide color and/or UV resistant additives. The extrusion units 102 are preferably formed by a continuous extrusion process, although other methods for producing thin-walled structures may be used, including injection molding and blow molding.

Referring now to FIG. 3, structural details and dimensions are provided for a preferred embodiment of an extrusion unit 102 suitable for use in an artificial timber similar to that shown in FIG. 1. In this embodiment, a single extrusion unit has an exterior height 302 of about 4 inches and an exterior width 304 of about 4 inches. The nominal wall thickness 306 is about 0.125 inches, and the interior radius 308 at each corner is about 0.125 inches. This results in an interior cavity width 310 of about 3.75 inches and an interior cavity height 312 of about 3.75 inches. The extrusion length in this preferred embodiment is about 40 inches. As will be further described herein, each end cap is 104 is about 8 inches in length, but overlaps the end of the extrusion unit 102 by about 2 inches. Thus, the finished overall length of an assembled standard length timber 100 in accordance with this preferred embodiment is about 52 inches, and the standard length between spike apertures 108 (i.e., the “spike-to-spike” distance) is about 48 inches.

Preferably, the components of the artificial landscape timber are all produced by high speed methods, namely, extrusion for the extrusion units 102, and injection molding for the end caps 104. These production methods allow the parts to be produced at high rates and for very reasonable cost. In contrast, production of conventional roto-molded artificial landscaping timbers is time consuming, and thus relatively expensive.

Referring now to FIGS. 4-7, there is illustrated an end cap 104 for use with the timber 100 of FIG. 1, which utilizes three stacked extrusion units 102. The end cap 104 is preferably a molded piece formed from HDPE or similar plastics. As best seen in FIG. 4, the walls of end cap 104 define a cavity on the proximal end of the end caps for receiving the ends of the extrusion units 102. The distal ends 118 of the end cap will preferably have a rounded profile as shown. FIGS. 5, 6 and 7 illustrate various views of the end cap 104.

Specifically, FIG. 5 is a top view of the end cap 104. It will be appreciated that the distal end of the unstepped portion (denoted 118′) and the distal end of the stepped portion 106 (denoted 118″) are generously radiused (when viewed from above) to allow a clearance for relative angular movement between timbers when the complimentary end caps of the timbers are connected using a securing spike inserted through aperture 108. In a preferred embodiment consistent with the use of three stacked extrusion members 102 of the type described in connection with FIG. 3, the end cap 104 has an interior cavity width 502 of about 4.05 inches to allow clearance over the end of the 4 inch extrusion unit 102 as shown in FIG. 3. This end cap has an exterior wall thickness of about 0.15 inches, resulting in an exterior width 504 of about 4.35 inches. The end cap in this embodiment has an overall exterior length 506 of about 8.0 inches. The distal ends 118″ and 118″ have radii 508 and 510, respectively, of about 2.175 inches. The spike aperture 108 has a diameter 512 of about 0.85 inches and is located a distance 513 of about 2.0 inches from the distal end 118″ of the stepped portion 106. The recess 112 has a width 514 of about 2.0 inches.

FIG. 6 is a rear view of the end cap 104. In a preferred embodiment consistent with that described in connection with FIGS. 3 through 5, the end cap 104 has an interior cavity height 602 of about 12.05 inches to allow clearance over the three stacked extrusion units 102 of FIG. 3. With the previously mentioned end cap wall thickness of about 0.15 inches, this yields an exterior height 604 of about 12.35 inches. The unstepped portion of the end cap has a height 606 of about 6.025 inches while the recess 112 surrounding the spike aperture 108 extends downwards into the interior of the end cap by a distance 608 of about 0.5 inches.

FIG. 7 is a side view of the end cap 104. In a preferred embodiment consistent with those described in connection with FIGS. 3 through 6, the end cap 104 will have an unstepped length 702 of about 4 inches and a stepped length 704 of about 4 inches. When properly installed, the ends of the extrusion units 102 will extend approximately one half way across the unstepped length of the end cap to the point denoted by a dashed line 706.

It will be appreciated that the dimensions provided for the embodiment described in connection with FIGS. 3 through 7 are representative of a single preferred embodiment only. It will be appreciated that additional embodiments with different dimensions among the various components are well within the scope of the current invention. It will further be appreciated that the structural dimensions and tolerances associated with such additional embodiments may be determined by a comparison of the dimensions and tolerances of similar components in the disclosed embodiments.

Referring now to FIG. 8, there is illustrated a landscaping timber in accordance with another embodiment of the current invention. Artificial landscaping timber 800 comprises extrusion units 102 and end caps 804 similar in most respects to those previously described for the embodiment of FIG. 1. However, timber 800 includes only two extrusion units 102 and has end caps 804 which are dimensionally adapted to receive only two extrusion units.

FIGS. 9-12 illustrate the end cap 804 adapted for use with the embodiment of FIG. 8. It will be appreciated that the end cap 804 is substantially similar in many respects to that of the end cap 104 shown in FIG. 4, however, the end cap 804 is dimensioned to receive only two extrusion units 102. FIGS. 10-12 show various views of the end cap 804 and provide preferred dimensions.

Specifically, FIG. 10 is a top view of the end cap 804. As with end cap 104, the distal end of the unstepped portion (denoted 118′) and the distal end of the stepped portion 106 (denoted 118″) are generously radiused. In a preferred embodiment consistent with the use of two extrusion members 102 of the type described in connection with FIG. 3, the end cap 804 has an interior cavity width 1002 of about 4.05 inches to allow clearance over the end of the 4 inch extrusion unit 102. The end cap 804 has an exterior wall thickness of about 0.15 inches, resulting in an exterior width 1004 of about 4.35 inches. The end cap in this embodiment has an overall exterior length 1006 of about 8.0 inches. The distal ends 118″ and 118″ have radii 1008 and 1010, respectively, of about 2.175 inches. The spike aperture 108 has a diameter 1012 of about 0.85 inches and is located a distance 1013 of about 2.0 inches from the distal end 118″ of the stepped portion 106. The recess 112 has a width 1014 of about 2.0 inches.

FIG. 11 is a rear view of the end cap 804. In a preferred embodiment consistent with that described in connection with FIGS. 3 and 8 through 10, the end cap 804 has an interior cavity height 1102 of about 8.05 inches to allow clearance over the two stacked extrusion units 102. With the previously mentioned end cap wall thickness of about 0.15 inches, this yields an exterior height 1104 of about 8.35 inches. The unstepped portion of the end cap has a height 1106 of about 4.025 inches while the recess 112 surrounding the spike aperture 108 extends downwards into the interior of the end cap by a distance 1108 of about 0.5 inches.

FIG. 12 is a side view of the end cap 804. In a preferred embodiment consistent with those described in connection with FIGS. 3 and 8 through 11, the end cap 804 will have an unstepped length 1202 of about 4 inches and a stepped length 1204 of about 4 inches. When properly installed, the ends of the extrusion units 102 will extend approximately one half way across the unstepped length of the end cap to the point denoted by a dashed line 1206.

It will be appreciated that the dimensions provided for the embodiment described in connection with FIGS. 10 through 12 are representative of another specific preferred embodiment only. As previously indicated, additional embodiments with different dimensions among the various components are well within the scope of the current invention, and the structural dimensions and tolerances associated with such additional embodiments may be determined by a comparison of the dimensions and tolerances of similar components in the disclosed embodiments.

It will be appreciated that artificial landscaping timbers having other configurations of stacked extrusion units are within the scope of the invention. Alternative embodiments may have four or more extrusion units stacked in a single column, or extrusion units stacked in rows and columns, e.g., four extrusion units stacked two high and two wide. The dimensions of the end caps are simply modified to correspond to the dimensions of the ends of the stacked extrusion units.

Referring now to FIG. 13, there is illustrated a perspective view of the artificial landscape timber 100 similar to that shown in FIG. 1.

Referring now to FIG. 14, there is illustrated a landscaping timber 1400 in accordance with yet another embodiment of the current invention. Artificial landscaping timber 1400 includes three extrusion members 102 and is substantially identical to timber 100 in most respects. However, one end of timber 1400 includes a non-stepped end cap 1404 rather than the standard stepped end cap 104 of previous embodiments.

Referring now also to FIG. 15, it will be appreciated that the non-stepped end cap 1404 defines a cavity 116 on the proximal side but has an unstepped exterior on the distal end 1418. This unstepped end cap 1404 allows the timber 1400 to be used to terminate timber walls when encountering fences, gates or other architectural features which do not require the stepped end of standard timbers. In the unstepped end cap 1404, the spike apertures 108 go through the top and bottom surfaces of the overall end cap as shown. Unstepped end caps 1404 may be dimensioned for timbers having either two or three stacked extrusion units 102. It will be appreciated that unstepped end caps 1404 may be interchanged with stepped end caps 104 or 804 as required for a particular job.

Referring now to FIGS. 16 a-16 d, there is illustrated an artificial landscaping timber system in accordance with yet another embodiment. The artificial timber 1600 of this system includes a plurality of elongated hollow extrusion units 1602, a pair of generally cup shaped end plates 1604 and 1605, and a plurality of end caps 1606. When completely assembled, the artificial timber 1600 of the current embodiment has an outward configuration and mode of employment that is similar in many respects to the artificial timbers previously illustrated, e.g., in FIGS. 1 and 8. However, the artificial timber system of the current embodiment replaces the unitary stepped end caps of the previous embodiments with separately formed end plates and unstepped end caps that further simplify the manufacture, adjustment and installation of the timbers 1600 and yields other advantages as described herein below.

The extrusion units 1602 of this embodiment are generally similar in cross-sectional configuration to those disclosed in connection with FIG. 3. Preferably, the extrusion units 1602 are formed of extruded rigid PVC having a flex modulus (ASTM Method D790B) of at least about 475,000 psi, and more preferably having a flex modulus within the range from about 475,000 psi to about 525,000 psi. In testing, extrusion units 1602 formed of extruded rigid PVC with a flex modulus of about 500,000 psi have performed well. The walls of 1608 of the extrusion unit 1602 define an interior cavity or bore 1610 having a generally constant cross section along the longitudinal axis. For the construction of timbers 1600 having a standard length (spike-to-spike) of 48 inches, extrusion units 1602 having a length of about 44 inches are required. In the embodiment shown in FIGS. 16 a-16 d, three extrusion units 1602 are disposed upon one another with their longitudinal axes parallel to form the “main body” of the timber 1600. In other embodiments, two, four or other numbers of extrusion units 1602 may be stacked to form timbers having different sizes.

The two end plates 1604 and 1605 are removably mounted (one at each end of the timber body) over the collective ends of the stacked extrusion units 1602, thereby aligning the extrusion units both vertically and horizontally. Referring now to FIGS. 17 a-17 b and 18, the end plates 1604 and 1605 include a generally flat end portion 1612 surrounded by a depending side wall 1614 dimensioned to encircle the end of the stacked extrusion units. Preferably, the dimensions and tolerances of the end plates 1604 and 1605 are selected to produce a snug interference fit over the end of the extrusion unit stack, i.e., a fit that allows the end plate to be mounted and removed by hand, but which prevents the plates from falling off when subjected to moderate vibration of the type encountered during shipping. As will be further described herein, the end plates 1604 and 1605 will be removably secured to the extrusion units 1602 with removable fasteners 114, e.g., screws of the like, after final positioning and assembly of the end caps 1606.

The flat end portions 1612 of the end plates 1604 and 1605 further define one or more apertures 1616, each of which aperture is dimensioned and disposed to reveal the bore 1610 of one of the underlying extrusion units 1602. In the embodiments shown, end plate 1604 includes two apertures 1616, one aligned with the bore of the upper extrusion unit and one aligned with the bore of the lower extrusion unit. End plate 1605 has only one aperture 1616, which is aligned with the bore of the center extrusion unit, making the end plate 1605 the “compliment” of end plate 1604 (and vice versa).

Referring now to FIG. 19, there is illustrated yet another end plate, denoted 1618, that includes three apertures 1616 so as to have one aperture aligned with each of the bores 1610 of three stacked extrusion units 1602. It will be appreciated that a side view of the one-aperture end plate 1605 and of the three-aperture end plate 1618 will be (with the exception of the number of apertures) substantially identical to the side view of the two-aperture end cap 1604 illustrated in FIG. 17 b.

While the three-aperture end plate 1618 could be substituted for either end plate 1604 or 1605 in the artificial timber 1600, this use is not preferred since it leaves some of the bores 1610 of the extrusion units 1602 open to the environment such that dirt and water can collect inside the unit. Instead, referring now to FIG. 20, the preferred use of the three-aperture end plate 1618 is in an alternate timber 1620, which has three end caps on one end, e.g., for use in a border termination. FIG. 20 also shows the timber 1620, which has a single-aperture end plate 1605 on the other end, interconnecting with a standard timber 1600 having complementary end plates 1605 and 1604 on either end as previously described. It will be understood that portions of the end caps 1606 in FIG. 20 are broken away for purposes of illustration to show the securing spikes 110 that interconnect the timbers 1620 and 1600 to one another and secure them to the ground.

Referring now to FIGS. 21 a through 21 d, there are illustrated further details of the unstepped end cap 1606 of this embodiment. The end cap 1606 has a body portion 2102 dimensioned to fit closely within the bore 1610 of the extrusion unit 1602. Preferably, the dimensions and tolerances of the end cap 1606 are selected to produce a snug (i.e., hand-tight) interference fit with the bore 1610 of the extrusion unit. The cap 1606 further includes a distal portion 2104 that is typically radiused in a fashion similar to that of the end caps 104 in the previous embodiment. The distal portion 2104 further includes a recess 2106 on the upper surface and a spike aperture 2108 formed vertically therethrough. The walls of the end cap 1606 typically define an internal cavity 2110 accessible from the rear of the cap, i.e., for molding purposes. In the embodiment shown, a reinforcing member 2112 is provided inside the cavity 2110 to strengthen the distal portion 2104 of the cap and to provide an additional (i.e., internal) spike aperture 2108. It will be appreciated that since the end caps 1606 are dimensioned to fit within the bores 1610 of the extrusion units 1602, then the end caps are also capable of passing through the apertures 1616 in the end plates 1604, 1605 and 1618.

The end plates 1604, 1605 and 1618 and the end caps 1606 are preferably molded from polymer materials as separate, one-piece elements, e.g., using injection molding or the like. While any engineering polymer can be used for these elements including vinyls, polyolefins, polyethylenes and styrenics, it is preferred to use tough, flexible polymer materials such as HDPE or polypropylene. In particular, it has been determined that making the end plates 1604, 1605 and 1618 and/or end caps 1606 from a polymer that is significantly more flexible (i.e., less rigid) than the material of the extrusion units 1602 will greatly reduce the tendency of the securing spikes 110 to pull out of the ground during use of the timbers. It is believed that the use of these relatively flexible interconnecting end portions reduces the magnitude of the torques and lifting forces transmitted between the relatively rigid longitudinal portions of the timbers 1600 and 1620 and the securing spikes 110.

For example, if the extrusion units 1602 in one embodiment are made from a material having a flex modulus (ASTM Method D790B) of about 500,000 psi, then the end caps 1604, 1605 and/or 1618 are preferably formed of a material having a flex modulus withing the range from about 252,000 psi to about 278,000 psi. In tests, timbers 1600 and 1620 having extrusion members made from a rigid PVC material having a flex modulus of about 500,000 psi and end plates and end caps made from a polypropylene material having a flex modulus of about 265,000 psi were found to greatly reducing spike pull out. Generalizing these results for the benefit of additional embodiments, it is believed that a spike pull out is materially reduced when the value of the flex modulus for the end cap material and/or the end plate material is less that about 56% of the value of the flex modulus for the extrusion unit material.

Referring now to FIG. 22, a partial cross-sectional view of the artificial timber 1600 is provided to further illustrate the construction features of the invention. The design of this embodiment makes it very simple to combine all of the components needed for a complete timber unit 1600 into a pre-assembly optimized for palletized shipping. First, as previously described, the three extrusion units 1602 are stacked on top of one another with the bores 1610 aligned. Next, while holding the extrusion units 1602 in alignment, the end plate 1604 is moved (as shown by arrows 2114) from its initial unmounted position (denoted “A” and shown in phantom line) to a mounted position (denoted “B”) fitted over the collective end of the stacked extrusion units. The second end cap 1605 (not shown) is next fitted over the opposite end of the stacked units in a similar manner. At this point, the extrusion units 1602 needed to make a single timber 1600 are stabilized and aligned by the end plates 1604 and 1605 without the need for fasteners. Next, an end cap 1606 is inserted through each aperture 1616 in the end plates 1604 and 1605 (as shown by arrow 2116) until entirely within the bore 1610 of the underlying extrusion unit 1602. This “retracted” position is shown by the end cap 1606 in the lower extrusion unit of FIG. 22. After all the end caps 1606 are inserted to the retracted position, the pre-assembly is complete and ready to be palletized for shipping. The pre-assembly includes all parts (except fasteners) necessary to make a timber 1600, the length of which can be easily reduced without the need for any optional or additional parts. Preferably, the fit of the end plates 1604 and 1605 over the outside walls 1608 of the extrusion units 1602, and the fit of the end caps 1606 within the bores 1610 of the extrusion units will be sufficiently tight to obviate the need for fasteners during shipping. If not, then removable fasteners (e.g., screws) can be used to hold the pre-assembly together.

Once the pre-assembly for timber 1600 reaches the installation site, final assembly can be performed. If the timber 1600 will be used at its standard length, final assembly proceeds as follows: First, the end caps 1606 are moved through the apertures 1616 in the end plates 1604 and 1605 (as indicated by arrow 2118) into an “extended” position with the distal portion 2104 including the spike aperture 2108 disposed outside the end plate, and with the body portion 2102 disposed within the bore 1610. This extended position is shown by the end cap 1606 in the upper extrusion unit of FIG. 22. It is not typically necessary, nor desirable, to remove the end plate 1604 or 1605 in order to move the end caps 1606 from the retracted position to the extended position. Rather, a hook (not shown) may be inserted through the aperture 1616, engaged into the spike aperture 2108 of the retracted end cap 1606, and then used to pull the end cap into the extended position. Once all end caps 1606 are in the extended position, removable fasteners 114, e.g., self tapping screws, are inserted through the now overlapping end plate side walls 1614, extrusion unit walls 1608 and end cap body portion 2102, thereby securing all of the timber components together in a semi-permanent fashion that will resist operational loads. In positions where no end cap is present, e.g., the middle position in FIG. 22, the fastener is preferably still inserted through the end plate side walls 1614 and extrusion unit walls 1608 to further reinforce the assembly.

If the timber 1600 is assembled at the installation site from individual components rather than from a pre-assembly, similar steps will be followed. However, after stacking the extrusion units 1602 and fitting the end plates 1604 and 1605, the end caps 1606 can be installed through the apertures 1616 directly into the extended position. The fasteners 114 can then be installed through the overlapping components as previously described and the timber 1600 is complete.

Reducing the length of the timber 1600 from the standard length is a very simple operation that requires no additional parts or optional adapters. If using a pre-assembly as described above, reducing the length of the timber proceeds as follows: First, the end plate must be removed at one end of the stack, and the end caps 1606 at that end must be pulled out of the bores 1610. Next, the extrusion units 1602 are cut off by a length equal to the amount of reduction required. Next, the end plate is re-fitted over the end of the (now shorter) stack of extrusion units 1602, and the end caps 1616 are re-inserted into the bores 1610 until in the extended position. Finally, the removable fasteners 114 are then inserted through the overlapping end plate side walls 1614, extrusion unit walls 1608 and end cap body portion 2102 to secure the reduced length timber together. It will be appreciated that this length reduction process did not require any additional components or adapters, only the parts normally present in a standard timber 1600.

Referring again to FIGS. 17 a-17 b, 18-20 and 21 b-21 d, dimensions are now given for the components of a preferred embodiment of the timber 1600 that uses three extrusion units 1602 configured as shown in FIG. 3 and having nominal external cross-sectional dimensions of about 4.0 inches by 4.0 inches. For this preferred embodiment, the end plates 1604, 1605 and 1618 have identical overall dimensions, with an exterior height 1702 of about 12.3 inches and an exterior width 1704 of about 4.25 inches. The sidewall portion 1614 has an external depth 1706 of about 1.74 inches. The internal dimensions for height 1708, width 1710 and depth 1712 are about 12.05 inches, 4.05 inches and 1.64 inches, respectively. Each aperture 1616 has height 1714 and width 1716 of about 3.75 inches each, corresponding with the dimensions of the bores 1610 of the extrusion units 1602. The apertures 1616 are positioned on the flat end portions 1612 of the end plates to match the position of the openings of the respective underlying bores 1610 when the end plates 1604, 1605 are 1618 are attached to the stack of extrusion units.

As best seen in FIGS. 21 b-21 d, the end caps 1606 of this preferred embodiment have an external height 2120 of about 3.73 inches, an external width 2122 (in the body portion) of about 3.73 inches, an internal height 2124 of about 3.48 inches, an internal width 2126 (in the body portion) of about 3.48 inches and an overall external length 2127 of about 6.0 inches. The distal portion 2104 has a radius 2128 of about 1.87 inches and the spike aperture 2108 has a diameter 2130 of about 0.85 inches. The recess 2106 has a width 2132 of about 2.0 inches, a depth 2136 of about 0.5 inches and a length 2138 of about 2.87 inches. The reinforcing member 2112 has a length 2140 of about 2.87 inches and is located at a distance 2142 above the lower wall of about 1.72 inches.

It will be appreciated that the dimensions provided for the specific preferred embodiment just described are not to be understood as required for all embodiments. As previously indicated, additional embodiments with different dimensions among the various components are well within the scope of the current invention, and the structural dimensions and tolerances associated with such additional embodiments may be determined by a comparison of the dimensions and tolerances of similar components in the disclosed embodiments.

While the invention has been shown or described in a variety of its forms, it should be apparent to those skilled in the art that it is not limited to those embodiments, but is susceptible to various changes without departing from the scope of the invention. 

1. A landscaping timber unit, comprising: at plurality of hollow extrusion units; each extrusion unit extending longitudinally from a first end to a second end thereof and having a bottom wall and an opposite top wall, and having opposite side walls extending between the top and bottom walls, the top, bottom and side walls collectively forming a substantially rectangular cross section when viewed along the longitudinal axis; the extrusion units being stacked upon one another with their respective first ends proximate to one another, with their respective second ends proximate to one another, and with their respective longitudinal axes substantially parallel to one another; a pair of end caps, one end cap being affixed to the first ends of the stacked extrusion units, and the other end cap being affixed to the second ends of the stacked extrusion units; each end cap having a first end configured to receive the end portions of the stacked extrusion units and a second end that includes an aperture for receiving an elongate rod-shaped spike therethrough such that the end of the timber unit can be secured to the ground by driving the spike through the aperture into the ground.
 2. A landscaping timber unit in accordance with claim 1, wherein the second end of at least one end cap is stepped such that the apertures are formed through portions of the end cap having a height about half the total height of the stacked extrusion units.
 3. A landscaping timber unit in accordance with claim 1, wherein the extrusion units are extrusions formed of a plastic material continuously extruded into a substantially rectangular cross section.
 4. A landscaping timber unit in accordance with claim 3, wherein the plastic material is primarily polyvinyl chloride (PVC).
 5. A landscaping timber unit in accordance with claim 1, wherein the extrusion units are formed of a first material having a first flex modulus, the end caps are formed of a second material having a second flex modulus, and the value of the second flex modulus is substantially less than the value of the first flex modulus.
 6. A landscaping timber unit in accordance with claim 5, wherein the value of the second flex modulus is less than about 56% of the value of the first flex modulus.
 7. An artificial landscaping timber comprising: a plurality of elongate extrusion units of equal length, each extrusion unit having a continuous wall that circumscribes a longitudinal axis so as to define an interior bore having a substantially constant rectangular cross section when viewed along its longitudinal axis, and having a rectangular opening at each longitudinal end of the wall, the plurality of extrusion units being juxtaposed in a single file with their respective longitudinal axes parallel to one another and with their respective longitudinal ends even with one another to form an extrusion stack having an external perimeter and longitudinal ends; a pair of end plates, one of the end plates being removably mounted on each longitudinal end of the extrusion stack, each end plate having a generally flat end portion surrounded by a side wall depending laterally therefrom, and further having at least one aperture formed through the flat end portion; the generally flat end portions of each end plate having dimensions substantially equal to the dimensions of the longitudinal end of the extrusion stack and lying generally perpendicular to the longitudinal axes of the extrusion units when mounted on the extrusion stack; the side walls of each end plate being dimensioned to encircle the external perimeter of the extrusion stack when mounted thereon so as to maintain the alignment of the extrusion units in the extrusion stack; the aperture(s) of each end plate each being disposed to overlie a single one of the the extrusion units and being dimensioned to form an opening at least as large as the interior bore of the overlain extrusion unit; a plurality end caps, each end cap extending through one of the apertures of the end plates and being removably mounted in the end of one of the extrusion units, each end cap having a body portion and a distal portion; the body portion of each end cap being dimensioned to fit within the bore of one of the extrusion units; and the distal portion of each end cap having an aperture formed therethrough for receiving a securing spike and remaining outside the bore of the extrusion unit when the end cap is mounted therein.
 8. An artificial landscaping timber unit in accordance with claim 7, wherein the extrusion units are formed of a first material having a first flex modulus, the end caps are formed of a second material having a second flex modulus, and the value of the second flex modulus is substantially less than the value of the first flex modulus.
 9. An artificial landscaping timber unit in accordance with claim 8, wherein the value of the second flex modulus is less than about 56% of the value of the first flex modulus.
 10. An artificial landscaping timber unit in accordance with claim 7, wherein the extrusion units are formed of a first material having a first flex modulus, the end plates are formed of a second material having a second flex modulus, and the value of the second flex modulus is substantially less than the value of the first flex modulus.
 11. An artificial landscaping timber unit in accordance with claim 10, wherein the value of the second flex modulus is less than about 56% of the value of the first flex modulus.
 12. An artificial landscaping timber unit in accordance with claim 7, wherein the extrusion units are formed of a rigid PVC (polyvinyl chloride) material and the end caps are formed of a HDPE (high density polyethylene) material.
 13. An artificial landscaping timber unit in accordance with claim 7, wherein the extrusion units are formed of a rigid PVC (polyvinyl chloride) material and the end caps are formed of a polypropylene material.
 14. An artificial landscaping timber unit in accordance with claim 13, wherein the rigid PVC material has a flex modulus (ASTM Method D790B) within the range from about 475,000 psi to about 525,000 psi and the polypropylene material has a flex modulus within the range from about 252,000 psi to about 278,000 psi. 